A barking drum of the general type defined above is described in Applicant's U.S. Pat. No. 4,369,823, issued Jan. 25, 1983. The barking drum described therein is the first of its kind enabling full trees to be treated so that the limbs and bark are removed during passage of the wood through the drum. The expression "full trees" means such trees which have not been limbed and barked, and are free or substantially free of root portions.
When removing the limbs and bark from the full trees, this is usually performed by feeding them into the drum in bundles of about 5 solid m.sup.3 biomass. Of this, about 35-45% is reject material, i.e. waste material in the form of limbs, needles, leaves and bark. In order to achieve an even better barking result with this known drum, it is therefore necessary to remove rejects from the first main treatment section in which most of the limbing is carried out, before the wood is passed on to the next main treatment section in which remaining bark is to be removed.
A particular problem arises when barking forest raw material from which the bark is difficult to remove, such as eucalyptus, since the bark is stripped from the wood in such lengths which are difficult to remove from the drum.